IN A NUTSHELL:Becauses it's often edited out by documentary makers. To keep the narrative flowing, they often summarize or edit footage. That’s why sometimes in documentaries there’s no speed-of-light delay in Apollo’s Earth-Moon communications. But the delay is there in the unabridged reference recordings and transcripts published by NASA.

THE DETAILS: In some footage of the Moon landings, the astronauts appear to answer the radio messages from Earth too quickly. Radio waves, traveling at the speed of light, take about a second and a quarter to cross the gap between the Earth and the Moon, so there should be at least an equivalent pause between the words uttered in Mission Control in Houston and the replies from the astronauts on the Moon. If there’s no delay, the radio transmissions must have been fake, argue some conspiracy theorists.

A less conspiratorial explanation is that the footage has been edited for conciseness or pacing with respect to the original recordings. Indeed, the lack of delay occurs in documentaries, but not in NASA’s source material. With very few exceptions, documentaries tend to omit unnecessary dialogue and use mismatched images to achieve a more dramatic and interesting narration by focusing on key moments. There’s no real intent to deceive, but the end result is that many documentaries are not as faithful as one might expect.

For example, the Apollo 11 lunar landing is often portrayed so that it seems that the very first words spoken on the Moon were “Tranquility Base here, the Eagle has landed”. Actually, if you go to the original recordings and transcripts (available at the Apollo Lunar Surface Journal website), it turns out that those famous words were preceded by a substantial chunk of technical reporting.

Here’s the unabridged transcript, starting from the very first contact with the lunar surface:

102:45:40 Aldrin: Contact Light.

Aldrin is telling Mission Control that the Lunar Contact warning light has turned on: this means that at least one of the 173-centimeter (68-inch) probes under the footpads of the Lunar Module has touched the ground. Technically, these are the first words spoken on the Moon.

Once the LM has settled on the surface, the series of technical status reports continues, as the spacecraft is prepared for its stay on the Moon:

It’s quite obvious that these status reports are of no interest to the average viewer: that’s why they often get cut in documentaries.

Another frequent example of a cut for narrative purposes occurs seconds later: Charlie Duke, momentarily tongue-tied by the excitement of the event, mispronounces the new name of the Lunar Module, i.e., Tranquility Base.

He starts to say “Roger, Twan...”, then pauses and corrects himself: “...Tranquility. We copy you on the ground. You got a bunch of guys about to turn blue. We’re breathing again. Thanks a lot.” In most documentaries this flub is edited out.

Even the famous phrase “One small step...” is often presented in the wrong context: it’s usually heard as we see Neil Armstrong jump down the ladder of the LM. But actually, in the original video recording Armstrong jumps down and lands on the LM footpad, without touching the ground, describes his surroundings, hops up the ladder again (to test that he will be able to get back up at the end of the moonwalk), jumps down again, and only then does he cautiously place his left foot on the surface of the Moon and utter the historic words (Figure 9-10).

Figure 9-10. Armstrong is about to set foot on the Moon. Frame from the partially restored edition of the live TV broadcast.

Conspiracy theorists persistently make the mistake of considering documentaries to be equivalent to official records. They are not; the only true reference material is constituted by the original raw data and footage.

The extent to which even prize-winning films, such as For All Mankind, present inaccurately and misleadingly images and sounds of the Apollo missions is detailed by spaceflight historian James Oberg’s article Apollo 11 TV Documentary Misrepresentations (Wall Street Journal, 1994).